How to Sharpen Double-Angle Mill Cutters

Double-angle cutters can be used on mills or lathes in a machine shop.

Double-angle cutters such as end mills are used on the mill for certain cutting operations. Over time, the profile and/or bottom of the end mill can become dull. Rather than just throwing it away, it can be resharpened and used over again. There are two angles that must be sharpened for the bottom to cut properly, so a special holder must be used to sharpen the cutter on a surface grinder. Once you sharpen the first angle, you must tilt the holder forward to sharpen the same area, but at a different angle.

Things You'll Need

• Precision vise
• Cut-off saw
• Surface grinder
• End mill sharpening holder
• Bench grinder
• Marker

Instructions

1. Examine the cutter to see where the wear exists and where you must cut it for resharpening. Double-angle cutters have profile-cutting capabilities, so you must cut off the dull area and resharpen the bottom of the cutter where the double-angle is located. Mark the spot where you will cut the end mill with a permanent marker.

2. Tighten the end mill in a precision vise and place it under the cut-off blade on the work table of the saw. Lower the saw blade to line it up with the mark you made. Turn the saw on and carefully cut through the end mill. Go slowly and stop if the end mill gets too hot or the blade starts to rip or crack. Start on one side and turn it around if the blade is too small. If the blade is large enough, cut the tip off in one operation.

3. Place the cutter in a double-angled holder. Slide it into a collet and tighten the collet in the holder. Turn the column of the holder until you hear a click and the cutter is lined so that there is one flute facing in every direction -- north, south, east and west. The holder has two angles so that the first and secondary angles can be ground on the end of the cutter. Place it flat on the surface grinder work table and engage the magnet to hold it in place.

4. Move the table so that the grinding wheel is just over the cutter. Turn the grinding wheel on and lower it until it just touches the top of the end mill; you will see the sparks. Reset the measuring micrometer to zero and slowly grind the first flute until you have created a new cutting edge. Reset the micrometer once again and raise the grinding wheel.

5. Turn the column again until a dull flute is in the same spot as the one you just sharpened and repeat the grinding process, stopping at zero once again. Repeat this process until all of the flutes are sharpened. Move the grinding wheel out of the way to disengage the magnetic table and set the holder for the second angle.

6. Push the holder forward so that the holder rests on the second angle, which is built into the holder. Move the table so that the grinding wheel is once again over the flute and repeat Steps 4 and 5.

7. Wait until the cutter is no longer hot, remove the cutter from the holder and bring it over to a grinding wheel. Grind the center of the end-mill tip as there may be material sticking up from the sharpening operation that will get in the way when you use it on the milling machine.

References

• Pico Sytsems: Sharpen End Mills